Method of making filters for cigarettes



United States Patent [54] METHOD OF MAKING FILTERS FOR CIGARETTES 7 Claims, 8 Drawing Figs.

[52] U.S.Cl 93/1, 13l/ll, 131/61 [51] lnt.Cl....; 831d [50] Field of Search 93/1 0; 131/209, l 1,61A

[56] References Cited UNITED STATES PATENTS 3,354,887 11/1967 Hall Primary Examiner-Bernard Stickney Attorney-Craig, Antonelli, Stewart & Hill ABSTRACT: Making filter cigarettes incorporating particulate filtering material enclosed in a compartment by a method including the step of pushing a filter stub endwise towards the.

tobacco rod to pack the filtering material better. Alternative ways are described.

PATENIED-BEII! slam- INVENTOR ATTORNEY METHOD OF MAKING FILTERS FQR CIGARE'I'IES This invention concerns improvements in or relating to filters for cigarettes, which-filters include particulate filtering material; the term cigarettes" being understood to include cigars, cigarillos and other smokable articles.

Such filters can be made by arranging 'stubs, i.e. cylindrical portions of fibrous or other air-permeable material, at spaced intervals on a paper strip which is folded to U-cross section, and feeding particulate material in loose form into the pockets formed by the bowed paper strip' and the opposite end faces of neighboring stubs, after which the paper strip is folded into tubular form about the' stubs and particulate material. Difficulty is, however, experienced in ensuring that enough particulate material is containedbetween two stubs to ensure that when the final-filter cigarette is'smoked, all the smoke passes through the particulate filtering material and none bypasses it. i

According to the present invention there is provided a method of making a smoke-filtering rod including the step of assemblingtwo smoke-permeable cylindrical elements to be embraced in a tubular wrapping together with particulate, filtering material between the two elements whereby the material is enclosed in a space defined between the two elements within the wrapping and including the step of causing the two elements to be relatively displaced to reduce the volume of said space and thereby increase the degree to which the material packs the space.

The two elements can on the one hand be filter stubs and I the method can include moving one stub towards the other to be displaced inwardly of an end of the wrapping to define a FIG. 4 represents an assemblage of two cigarette lengths the cylindrical paper wrapper 6 of the filterZ, are firmly.

secured by adhesive to the uniting band 3. However, the outer stub 4, although held in position by the wrapper 6, is not stuck to it at this stage but can be moved endwise within it, and in accordance with the invention is moved inwardly towards the inner stub 5, thus reducing the space between the two stubs and ensuring that this space is substantially entirely filled by the loose particulate material 7. Asa result of this inward movement a hollow recess 8 is left at the end of the filter.

' An alternative method is illustratedin FIGS. 2AC. The

outer stub 4 in this instance is initially longer than required, and when it has been moved inwardly as shown in FIG. 28, it is trimmed by being cut through along the line C-C. This reduces the stub to the length required and-also produces a flush end as illustrated in FIG. 2C.

In both the examples described above, the filter cigarettes may be produced by first producing an assemblage consisting of a double-length filter between two cigarette lengths as illustrated in FIG. 4. This assemblage is subdivided by cutting through the central double-length stub 4A, which divides into The two elements can on the other hand be a filter stub and a wrapped tobacco rod whereby a filter cigarette is produced.

The method can include coating the inner face of the wrapping with adhesive of anature such as to permit movement of a smoke-permeable element within the wrapping and to be capable of subsequently being caused to secure the stubs to the tube. The adhesive can be heat-scalable and include the step of heating the rod to seal the adhesive.

The invention also includes a method of making filter cigarettes comprising subdividing an assemblage consisting of a double-length filter between and joined to two cigarette lengths and using any of the methods described above to form the filter. This method of making filter cigarettes can include fonning the double length filter to comprise .three filter stubs spaced apart within a tube the two spaces between them containing particulate material and the central. stub of the three being of at least double the length required in the endmost stub of the filter of a cigarette and moving the two endmost stubs inwardly towards each' other. It can also include trimming the ends to present flush end faces or the stubs can be moved inwardly of the ends of their'wrapping and the-filter cigarettes can be formed to have a hollowspace between the tobacco and the adjacent filter stub. 1

The invention extends to cigarette filters and filter cigarettes produced by the methods described.

' Filter cigarettes and filters and methods of producing them will now be described by way of example with reference to the accompanying diagrammatic drawing, in which:

FIGS. 1A and 18 represent two stages inthe production of a filter cigarette; I

FIGS. 2A, 2B and 2C represent three stages in the production of a filter cigarette by an alternative method;

FIGS. 3A and 38 represent two stages in the production of a filter; and

two outer stubs 4. It is contemplated that the operations described above with reference to FIGS. 1A and B and 2A-C are to be performed immediately or soon after the assemblage as illustrated in FIG. 4 has been subdivided.

FIGS. 3A and B illustrate a further example in which the endwise displacement of stubs is effected at an earlier stage of manufacture, i.e. before a double-length filter is joined to two cigarette lengths as shown in FIG. 4. FIG. 3A shows a doublelength filter comprising a double-length stub 4A (which eventually will divide into two outer stubs 4) and two stubs 5A, the latter being a little longer than will be required in the final product. The two stubs 5A are pushed inwardly towards each other within the tube 6, as shown in FIG. 3B, and are then trimmed by cutting at the lines C-C.

As an alternative, in a case where single-length filters are to be joined to single cigarette lengths, for example by a relatively narrow uniting band, single-length filters can be treated in a similar way to that just described in relation to a double-length filter. That is, both stubs in the single-length filter can be moved towards each other and the filter trimmed at both ends, or only one stub could be moved towards the other. The stubs are in such a case initially of a suitable length to allow for the trimming.

As an alternative to trimming the stub 4 in FIG. 313, it may be preferred in some instances to leave the end of the filter recessed so that in the final filter cigarette there will be a hollowchamber between the cigarette and the stub 5A. If this is done, the tube enclosing the stubs should be of sufficiently rigid material to enable a firm filter cigarette to be produced. Similarly the method in which single-length instead of doublelength filters are treated as described above could be modified by omitting the step of trimming ofa hollow chamber is desired between the cigarette and its neighbouring stub.

In all the examples described above, the tube 6 should preferably be coated with an adhesive material which can be made effective after the stubs have been moved inwardly as described, e.g. a heat-sealing material may be used which will finally secure the stubto the inner surface of the tube and prevent further movement.

I claim:

1. A method of making a smoke-filtering rod comprising assembling two smoke-permeable cylindrical elements with particulate filtering material between the two elements in a tubular wrapping having an adhesive coating on the inner face thereof whereby the material is enclosed in a space defined between the two elements within the wrapping, relatively displacing the two elements towards each other to reduce the volume of said space and thereby increase the degree to which said filtering material packs the space, and causing said adhesive to secure the elements to the tube.

2. A method according to claim 1 wherein the adhesive is heatsealable and said step of causing said adhesive to secure the elements to the tube comprises heating the rod to seal the adhesive following movement of the elements.

3. A method according to claim 1 wherein the two elements are filter stubs, one of said stubs being relatively displaced inwardly of an end of the wrapping towards the other stub whereby a recessed end space is fonned.

4. A method according to claim 3 wherein said one stub which is moved towards the other stub is longer than is required in the final smoke-filtering rod, said method comprising subsequently cutting through said longer stub and its enclosing wrapping to trim the filter to reduce the length of the stub to a predetermined length and to produce a neat, nonrecessed end face.

5. A method of making a double-length smoke-filtering rod comprising assembling three cylindrical filter stubs spaced apart within a tube with particulate filtering material contained in the two spaced between the three stubs, the central stub of the three being at least double the predetermined length of the endmost stub of the filter of a cigarette, relatively displacing the two stubs at opposite ends of the wrapping towards the central stub to reduce the volume of said spaces and thereby increase the degree to which said filtering material packs the two spaces and recessed end spaces are formed and trimming the ends to present flush end faces.

6. A method of making a smoke-filtering rod comprising assembling two smoke-penneable cylindrical elements with particulate filtering material between the two elements in a space defined between the two elements within the wrapping, one of said elements being longer than is required in the final smokefiltering rod, relatively displacing said longer element inwardly of an end of the wrapping towards the other elements to reduce the volume of said space and thereby increase the degree to which said filtering materialf packs the space whereby a recessed end space is formed, and subsequently cutting through said longer element and its enclosing wrapping to trim the filter to reduce the length of the stub to a predetermined length and to produce a neat nonrecessed end face.

7. A method of making a double-length smoke-filtering rod comprising assembling three cylindrical filter stubs spaced apart within a tubular wrapping a tubular wrapping with particulate filtering material contained in the two spaced between the three stubs, the central stub of the three being at least double the predetermined length of the endmost stub of the filter of a cigarette and said wrapping having an adhesive coating on the inner face thereof, relatively displacing the two stubs at opposite ends of the tube towards the central tube to reduce the volume of said spaces and thereby increase the degree to which said filtering material packs the two spaces, and causing said adhesive to secure the elements to the tube. 

